Load testing service Load Impact has released a Google Chrome extension to let API developers record API engagement direct from the browser. API developers can then run these recorded use cases through a variety of load testing scenarios to ensure reliable API access ahead of any plans to scale API delivery. Load Impact CTO Robin Gustafsson spoke with ProgrammableWeb about the new service feature.

"This new extension for the Chrome browser makes it very simple to record anything that's happening in an open tab," Gustafsson said.

"For example, you can use the Postman REST client - a Chrome extension for interacting with REST APIs - to record what happens when talking to your API. You can record a few types of typical user test cases direct from the browser and then combine them in a scenario for load testing. All you need is a copy of our API key, download our Chrome extension, and then the things you record via our Chrome extension will be automatically transferred and available when you next configure your load performance tests in Load Impact."

Gustafsson says the new extension makes it easier to record example test cases of how potential developer-consumers will use a provider's API. "Load Impact already has the feature of allowing a recording of user behavior, but it is via a proxy, which requires you to change all of your proxy settings in your browser or system preferences."

Use cases are at the basis of useful load performance testing, Gustafsson said. In most cases, if an API provider is looking to expand from a private beta release to a general availability release, or if promoting an API in a new market, or making an API available at a popular hackathon, API providers can record actual use cases direct from the web browser. Once these have been recorded, they are available in Load Impact to form the basis of running user scenarios. These scenarios allow API providers to simulate the response under particular conditions such as heightened potential levels of usage. "This gives you a more realistic picture of how your system would cope with realistic - but amplified - traffic patterns," Gustafsson said.

Gustafsson provided a set of screenshots to demonstrate how the Load Impact extension works with the Postman extension to record an API call use case:

Gustafsson also said the service could be used with private beta users or other early adopters.

"You could create a project account in Load Impact and then share the same API key with each early adopter. Then when they interact with your API via their browser, their real use cases will be recorded in your Load Impact account. You can even edit the preview of what has been recoprded so if someone made a bad request you can change that before you send it to our servers. As soon as you record the use cases, the only thing you need to consider is the traffic scenarios."